export function downloadFile(blob, fileName) {
  if('download' in document.createElement('a')) { // 非IE下载
    const elink = document.createElement('a')
    elink.download = fileName
    elink.style.display = 'none'
    elink.href = URL.createObjectURL(blob) // 创建一个临时的url指向blob对象
    document.body.appendChild(elink)
    elink.click() // 下载文件
    URL.revokeObjectURL(elink.href) // 释放URL 对象
    document.body.removeChild(elink)
  } else {// IE10+下载
    navigator.msSaveBlob(blob, fileName)
  }
}
